It isn't easy. It's always has a significant failure rate. Sometimes failure means almost certain death. Also, I think assassinate is much easier to avoid than bash/flurry/bat/flyto-murder/etc. I haven't run into many douchey assassins, but that's a data pool of 1.

I also don't think PWK needs changing. I haven't played a necro in a long time, but I remember it being pretty rare to kill and coming with a decent timer. If you're really worried about it, through on some extra saves when the PWK necro is in range. Again, easier to avoid than bash/flurry/bat/flyto-murder/etc.

I think I've been assassinated 2-3 times in ~1.5 decades. I don't think I've ever died to PWK. I've been bashed to death dozens of times. I've been flurried to death in the double digits. I have had practically instant death from snare and ambush more than assassinate or PWK. I feel like the small chance of death to either of these skills adds to the excitement game, just like bash/flurry/bat/flyto-murder/etc.

Carrion Fields!
By what name do you wish to be mourned?